/*
   This program just puts a small routine on the timer IRQ to increment a
   byte on screen. Three methods are demonstrated. The first is the most
   convenient, using a C function for the IRQ handler. The second allows you
   to set up a normal protected mode IRQ handler without worrying about it
   getting control from real mode. The third allows you to set up your own
   handler for real mode for minimum latency.
*/

/*北北北北北北北北北北北北北北北北北北北北北北北北北北北北北北北北北北北北北北
  INTERFACE
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#include "pmc.h"

extern DWORD irqrmiaddx;

void irqc (void);
void irqi (void);

/*北北北北北北北北北北北北北北北北北北北北北北北北北北北北北北北北北北北北北北
  CODE
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//屯屯屯屯屯屯屯屯屯屯屯屯屯屯屯屯屯屯屯屯屯屯屯屯屯屯屯屯屯屯屯屯屯屯屯屯屯屯
void __cdecl PMmain (void)
{
  SELOFF opmiv;
  SEGOFF ormiv;
  PTR p;

//----------------------------------------------------------------------------
// Set up a C function as an IRQ handler, wait for a keypress, then reset.

  dosputstr ("C function IRQ handler.\r\n");
  p = setirq (0, &ormiv, &opmiv, NULL, NULL, irqc, IRQC);
  getch ();
  resetirq (0, &ormiv, &opmiv, p);

//----------------------------------------------------------------------------
// Set up a normal IRQ handler, wait for a keypress, then reset.

  dosputstr ("Normal IRQ handler.\r\n");
  p = setirq (0, &ormiv, &opmiv, NULL, NULL, irqi, IRQI);
  getch ();
  resetirq (0, &ormiv, &opmiv, p);

//----------------------------------------------------------------------------
// Set up a normal protected mode IRQ handler and a seperate real mode IRQ
// handler, wait for a keypress, then reset.

  dosputstr ("Own real mode IRQ handler.\r\n");
  p = setirq (0, &ormiv, &opmiv, NULL, irqrmiaddx, irqi, IRQOWN);
  getch ();
  resetirq (0, &ormiv, &opmiv, p);

//----------------------------------------------------------------------------
// The same thing again, but just to demonstrate what that NULL parameter is.

  dosputstr ("Same thing.\r\n");
  p = lomalloc (IRQOWNLEN);
  setirq (0, &ormiv, &opmiv, p, irqrmiaddx, irqi, IRQOWN);
  getch ();
  resetirq (0, &ormiv, &opmiv, p);
}

/*鞍鞍鞍鞍鞍鞍鞍鞍鞍鞍鞍鞍鞍鞍鞍鞍鞍鞍鞍鞍鞍鞍鞍鞍鞍鞍鞍鞍鞍鞍鞍鞍鞍鞍鞍鞍鞍鞍
  C IRQ 0 handler function that increments a byte on the screen.
  Notes:
  ) Does not chain to the old handler.
鞍鞍鞍鞍鞍鞍鞍鞍鞍鞍鞍鞍鞍鞍鞍鞍鞍鞍鞍鞍鞍鞍鞍鞍鞍鞍鞍鞍鞍鞍鞍鞍鞍鞍鞍鞍鞍鞍*/
void irqc (void)
{
  (*(BYTE *)rlp (0xb8000)) ++;

  asm
  {
    mov al,20h
    out 20h,al
  }
}